Refactoring is improving the design of existing code. It shouldn't change behavior.
And regardless, the way you prevent loss of important functionality isn't by hoping people read docs that no longer exist. It's by writing coarse-grained tests that makes sure the software does the important things. If a programmer wants to change something that breaks a test like that, they go ask a product manager (or whatever you call yours) if that feature still matters.
And if nobody can say whether a feature still matters, the organization doesn't have a software problem, it has a serious management problem. Not all the coding techniques in the world can fix that.
And regardless, the way you prevent loss of important functionality isn't by hoping people read docs that no longer exist. It's by writing coarse-grained tests that makes sure the software does the important things. If a programmer wants to change something that breaks a test like that, they go ask a product manager (or whatever you call yours) if that feature still matters.
And if nobody can say whether a feature still matters, the organization doesn't have a software problem, it has a serious management problem. Not all the coding techniques in the world can fix that.